Melt chocolate over low heat. Set aside. Beat egg whites with salt until foamy. Gradually add sugar beating continuously until stiff and glossy. Beat in vinegar and vanilla. Fold in melted chocolate and nuts. Drop by teaspoonfuls on ungreased cookie sheet. Bake in 350-degree oven 10 minutes. Cool on rack. Makes about 3-1/2 dozen cookies. Reprinted with permission from: Powdered Sugar Cookies from the C and H Sugar Kitchen by Jean Porter Electronic format by Karen Mintzias